1. Field of the Invention
The present invention relates to a process for haze-free polishing of semiconductor wafers or slices in a one-stage process in which a polishing sol or gel, or an alkaline polishing agent containing solid polishing components is applied to the polishing cloth in the initial phase.
2. Description of the Prior Art
Such a process is described in the German Offenlegungsschrift No. 2,531,431 or the corresponding U.S. Pat. No. 4,070,799. In the final phase of the process, that is to say, the phase of the polishing operation in which the actual haze-free polish is effected, a polishing agent additive comprising 0.1 to 10% by weight, based on the polishing agent, of an anion-active and/or non-ionogenic tenside containing no nitrogen in the molecule is added to the polishing agent of the initial phase. Since with this procedure, however, the tensides remaining in the polishing cloth may reduce the polishing removal of the first stage in the case of a subsequent batch of semiconductor slices, it is recommended that the polishing process be carried out as a two-stage process, i.e. separately on two different polishing machines and in a polishing stage effecting the removal and a polishing stage effecting the haze-free polish.
In the method described in German Offenlegungsschrift No. 2,247,067 or the corresponding U.S. Pat. No. 3,874,129, a two-stage process is also carried out. A polishing suspension to which 1 to 10% by volume of a monohydric alcohol containing 3 to 5 carbon atoms and 0.01 to 0.5% by weight of polyvinyl alcohol are added is used in the second stage. However, both the processes, which are very efficient per se, yield excellent results, for example, in relation to the removal rates and the freedom from haze of the wafers obtained, as two-stage processes.